The present invention generally relates to a method and transportable environment for detecting vehicle noises and vibrations in dynamic situations. More specifically, the present invention relates to a method and transportable apparatus for detecting system imbalances in a drive line assembly for an automotive vehicle in a controlled environment that is insulated from ambient temperature and noise.
The individual components of a drive line system often include inherent or residual imbalances due to variations in manufacturing tolerances. While steps can be taken to balance the individual components, residual imbalances often still remain. When the individual components are assembled into the drive line system, the residual imbalances can xe2x80x9cstack upxe2x80x9d such that they combine to produce a relatively high level of imbalance. Automotive drive line systems which embody these characteristics are unacceptable because they produce drive line vibration and boom.
It is known in the related art to balance the drive line system prior to installation into the vehicle. Many fixtures are known in the art for performing this function and typically rely on vibration measuring devices physically coupled to the drive line system to identify and thereafter correct the imbalances. Still, this is often not enough to eliminate objectionable vibration in the drive line system of a fully assembled automotive vehicle. Thus, devices have been proposed in the related art which seek to identify and correct drive line system imbalances at the terminal stage of vehicle production and prior to shipment of the vehicle. However, these devices suffer from the disadvantage that an additional step in the manufacturing process must be added in order that vibration sensing instrumentation can be physically coupled to the drive line system of each vehicle. This is time consuming and labor intensive. In short, drive line system balancing as employed in the related art for a fully assembled automotive vehicle is presently not cost effective.
U.S. Pat. No. 5,641,904 to Kopp, et al, which is assigned to the assignee of the present invention and is hereby incorporated by reference into the present application, describes an apparatus which can detect and perform drive line system balancing in a fully assembled automotive vehicle in high volume production environments which is transparent to the current workload. The apparatus of the ""904 patent does not rely on the physical attachment of vibration sensing instrumentation to the automotive vehicle in order to detect and correct system imbalances.
U.S. Pat. No. 6,131,454 to Kopp et al, is also assigned to the assignee of the present invention and is hereby incorporated by reference into the present application. The ""454 patent describes an apparatus which can detect and perform drive line system balancing in a fully assembled automotive vehicle in high volume production environments which is transparent to the workload, just as the apparatus from the ""904 patent. However, the apparatus of the ""454 patent is transportable, thereby being adapted for transport to remote locations to perform on-site checks of Noise, Vibration, and Harshness (xe2x80x9cNVHxe2x80x9d) of a rolling vehicle.
The above methods and apparatus are not adapted to provide vehicle testing in a controlled environment. Therefore, there is a need in the industry for a transportable apparatus to test drive line imbalances in an assembled automotive vehicle that provides a controlled environment to insulate the test from ambient weather, temperature and noise.